Extraction and fractionation of petroleum resins with n-butanol



6, 1955 J. A. KIERAS 2,725,192

EXTRACTION AND FRACTIONATION OF PETROLEUM RESINS WITH N-BUTANOL Filed Oct. 9. 1952 A TTES T: IN VEN TOR. JOSEPH A. KIERAS BY M; 4 4%! A TTORNE Y EXTRACTION AND FRACTIONATION OF PETRO- LEUBI RESINS WITH N-BUTANUL Joseph A. Kieras, New London, Pa., assignor to The Atlantic Refining (Iompany, Philadelphia, Pa, a corporation of Pennsylvania Application October 9, 1952, Serial No. 313,861

4 Claims. ((11. 196-444) This invention relates generally to methods for separating plastic substances known as petroleum resins from petroleum fractions. In one particular embodiment, this invention is concerned with the extraction of petroleum resins from propane precipitated asphalts.

In the production of lubricating oils from asphaltic crudes, the common practice is to distill the crude oil to remove the light fractions present, such as gasoline, kerosene, and gas oil, and then to contact the residue containing the lubricating oil fractions and asphalt components with a solvent capable of dissolving the lubricating oil fractions, but in which the asphalt components are insoluble. Although a large number of solvents have been proposed for carrying out this separation, it has been generally found that those hydrocarbons which are normally gaseous at ordinary temperatures and pressures are capable of eifecting the most efiicient separation of the asphaltic bodies and carbonaceous materials present in the asphaltic residues. These normally gaseous hydrocarbons include such compounds as ethane, propane, butane, or mixtures thereof.

In the production of lubricating oils from asphaltic residues produced by distilling asphalt base crude oils and removing the gasoline, kerosene, and gas oil fractions, it is customary to separate the asphalt from the oil by commingling the asphaltic residue with the liquefied, normally gaseous, hydrocarbons under sufiicient pressure to maintain these hydrocarbons in the form of a liquid and then to separate the oil dissolved in the liquefied, normally gaseous, hydrocarbon from the insoluble asphaltic components. Where liquid propane is employed as the asphaltic precipitant and the lubricating oil solvent, a pressure of about 100 to 400 pounds per square inch is sufiicient to maintain this light hydrocarbon fraction in the form of a liquid, at a process temperature of 50 to 175 F. Under most circumstances, it has been found that about 2 to 15 volumes of liquid propane to 1 volume of the asphaltic oil is the proper ratio of these two materials, in order to effect satisfactory separation of the asphaltic materials present. The propane precipitated asphaltic components resulting from the above treatment are of little economic value and are generally blended off as a very high viscosity component in fuel oils, such as Bunker C fuel oil, or utilized as inexpensive laminants, binders, or fillers.

It is an object of this invention to produce from propane precipitated asphalts a variety of valuable petroleum resins. It is a further object of this invention to produce a variety of valuable petroleum resins from propane precipitated asphalt by utilizing simple equipment and moderate process conditions.

The asphaltic components to be treated according to the process of the instant invention are obtained in the following manner. Asphaltic crude oils are first distilled to remove the light materials present, such as gasoline, kerosene, and gas oil. The residue remaining after the 2,726,192 Patented Dec. 6, 1955 removal of these light fractions is then contacted with an asphalt precipitating solvent, such as propane, in a suitable contacting zone. This mixing operation may be carried out in either a batchwise or continuous manner, although continuous countercurrent extraction procedures are preferred. The propane is preferably under a pressure of about to 400 pounds per square inch and at a temperature of about 50 to F. From 2 to 15 parts of liquid propane to 1 part of asphaltic residue are usually satisfactory. It will be understood that the above limits may be modified as desired, depending upon the character of the particular residue undergoing treatment. The two products of this propane contacting operation are (l) a deasphalted lubricating oil fraction, and, (2) a precipitated asphalt fraction.

The deasphalted lubricating oil fraction contains a substantial amount of propane, as well as small quantities of asphaltic and resinous components. This fraction may be further purified and treated by a number of procedures which will not be set forth here since the treatment or further purification of this fraction forms no part of the present invention.

The aforementioned precipitated asphalt fraction or propane precipitated asphalt fraction is removed from the propane treating step and further treated, according to the process of this invention, so as to separate therefrom a variety of valuable petroleum resins in a practical and economical manner. Broadly, this further treatment to obtain petroleum resins comprises the steps of admixing the propane precipitated asphalt with from 1 to 20 volumes of n-butanol, agitating the mixture if desired, and separating a plurality of selected n-butanol-petroleum resin fractions by progressively lowering the temperature of the n-butanol-petroleum resin solution.

The present invention will be more fully understood from the description given with reference to the accompanying drawing which illustrates diagrammatically a continuous extraction system for suitably carrying out the instant process.

Referring to the drawing, a charge stock comprising propane precipitated asphalt, suitably prepared by the previously described propane deasphalting methods and preferably containing a minimum amount of propane, is introduced in liquid condition through line 1, into extraction column 2, at a point near the bottom of the column. Although the exact temperature of the charge stock entering the column is not critical and may be varied depending upon the source and method of preparing it, best results have been obtained when the charge stock is in a molten or liquid condition-for example, between 225 and 275 F. A stream of n--butanol is introduced through line 3, into fractionation column 2, at a point near the bottom of the column and at a point below the introduction of the charge stock. The charge stock entering through line 1 tends to flow downwardly, while the n-butanol entering through line 3 tends to flow toward the top of the column because of the difference in their specific gravities. As the charge stock descends and the n-butanol solution ascends, the n-butanol, which is preferably heated to a temperature slightly below its boiling point, extracts petroleum resins which are present in the propane precipitated asphalt. This extraction is facilitated by perforated plates 4, or similar baffle or contact devices which will permit more intimate and thorough contact between the two entering streams.

The propane precipitated asphalt which has been stripped of a major portion of its petroleum resins descends to the lower portion of the extraction column and is withdrawn through line 5. The maintenance of a quiescent settling zone at the bottom of the extraction column facilitates this withdrawal. The n-butanol which is present in the solution leaving through line may be recovered in any wellknownmanner and recycled to line 3. The primary components of the stream leaving through line 5 will be asphaltenes and the dark undesirable resins of extremely high molecular weight.

The n-butanol solution of petroleum resins resulting from the aforementioned contact between the charge stock and n-butanol rises upwardly through column 2. The upper portion of the extraction column 2 is divided into any desired number of sections by bafiles, plates, or inclined trays. Examples of such plates are shown in the drawing by numbers 6, 7, 8, and 9. Adjacent to each plate within the column (and preferably directly above each plate) there is located a cooling coil or equivalent device, such as is represented in the drawing by numbers 10, 11, 12, and 13. The function of these cooling coils and plates is to separate the ascending n-butanol solution of petroleum resins into a plurality of different fractions. For example, the ascending n-butanol solution of petroleum resins rising from the initial contact zone A may be at a temperature of 240 F. As this hot stream rises above inclined plate 6, it encounters cooling coil 10, and is cooled thereby from a temperature of 240 F. to a temperature of 200 F. This cooling of the n-butanol-petroleum resin stream causes the heaviest petroleum resins to precipitate out of solution and to fall upon inclined plate 6. The thus precipitated resins may be withdrawn through outlet14. Thereafter the n-butanolpetroleum resin solution at a temperature of 200 F. rises to a point above the next higher inclined plate 7, where it is cooled to a temperature of 145 F. by cooling coil 11. Again a portion of the resins will precipitate out, fall upon inclined plate 7 and be withdrawn through outlet 15. This procedure is continued any desired number of times until at the top of the column, where the lowest temperature exists, there is removed through outlet 18 an n-butanol solution containing the lightest resins.

The'precipitated resins which are removed through lines 14, 15, 16, and 17, are usually in the form of a viscous liquid and the n-butanol which is admixed therewith may be removed by any suitable means, such as stripping or distillation, and recycled for further use in the process while the resins themselves may be further purified by solvent refining, acid treating, and/or clay percolating.

It will be undertood that the temperatures set forth in the previous paragraphs, as well as the specific extraction apparatus shown in the drawing, are by no means intended to restrict the present invention since it is obvious that changes and modifications of the particular conditions and arrangements set forth will readily occur to the expert without departing from the spirit of my invention.

The resin fractions isolated from propane precipitated asphalt by the above processing will encompass a range of molecular weight from 400 to 1200, A. S. T. M. (D36-26) Ring and Ball softening points from 60 F. to 200 F., refractive index Na at 176 F. of 1.4900 to 1.6200, specific gravity of 0.9900 to 1.0600, and 0., D. Color from 0 to 200,000 (Optical Densitydefined by Ferris and McIlvain, Ind. and Eng. Chem, vol. 6, p. 3 (1934). The resins find utility in a number of applications, such as fillers, binders, adhesives, laminants, etc.

The following table is presented to illustrate the resins which were obtained by extracting a propane precipitated asphalt from a typical mixed-base Mid Continent crude resins at 200 F.-with 4 volumes of n-butanol per volume of asphalt, utilizing progressively decreasing temnerature precipitation techniques.

Table Precipis tation R. at Pecmc 0. D. smmmg out N Tempera- 176 F. Color f ji 1. 5834 1. 0246 139, 000 143 l. 5724 1. 0125 76, 000 117 1. 5720 l. 0151 61, 540 111 l. 5701 1. 0150 0 96 The use of n-butanol as the extractant in the process appears to be of the greatest importance as far as the utilization of decreasing temperature precipitation techniques are concerned. n-Butanol is the only solvent which has been found which will permit a number of selective cuts of petroleum resins to be made at temperatures ranging between room temperature and the softening temperature of propane precipitated asphalts with out the necessity of employing high pressures or low temperatures. In other words, n-butanol has the unique property of possessing a maximum selectivity for the more desirable petroleum resins at the most desirable and economical processing conditions. On the other hand, alcohols containing more than 4 carbon atoms per molecule or less than 4 carbon atoms per molecule have been found to possess either too little solvent power or too little selectivity for the successful separation of petroleum resins into a number of cuts. Similarly, other solvents, such as ethyl acetate, have too great a solvent power and very little selectivity.

The present invention therefore provides a novel, practical, and economical method for obtaining a variety of valuable petroleum resin from propane precipitated asphalts which can be carried out in simple and inexpensive apparatus.

I claim:

1. The method of producing a variety of petroleum resins which comprises contacting a propane precipitated asphalt fraction with n-butanol in an extraction zone, removing a fraction of propane precipitated asphalt which has been at least partially stripped of petroleum resins, and separating from the remaining n-butanol solution of extracted resins a plurality of petroleum resin fractions by progressively decreasing the temperature of said n-butanol solution of petroleum resins from about 240 F. to about room temperature.

2. A method according to claim 1 wherein between 1 and 20 volumes of n-butanol are contacted with each volume of propane precipitated asphalt in the extraction zone.

3. The method of producing a variety of petroleum resins which comprises intimately contacting a propane precipitated asphalt fraction with n-butanol, removing a first fraction of propane precipitated asphalt which has been at least partially stripped of petroleum resins, separating a second fraction comprising n-butanol solution of petroleum resins, passing said second fraction through a plurality of zones of progressively decreasing temperature ranging between about 240 F. and room temperature, and removing from each of said zones a solution of petroleum resins which has settled therein.

4. Petroleum resins prepared according to the method of claim 1, ranging between 400 and 1200 in molecular weight, 60 F. and 200 F. in ASTM (D36-26) Ring and Ball softening point, 1.4900 and 1.6200 in refractive index Nd at 176 F., and 0.9900 and 1.0600 in specific gravity.

References Cited in the file of this patent UNITED STATES PATENTS 2,031,234 Swift Feb. 18, 1936 2,114,796 Crawley Apr. 19, 1938 2,131,205 Wells et al. Sept. 27, 1938 2,500,757 Kiersted Mar. 14, 1950 

1. THE METHOD OF PRODUCING A VARIETY OF PETROLEUM RESINS WHICH COMPRSES CONTACTING A PROPANE PRECIPITATED ASPHALT FRACTION WITH N-BUTANOL IN AN EXTRACTION ZONE, REMOVING A FRACTION OF PROPANE PRECIPITATED ASPHALT WHICH HAS BEEN AT LEAST PARTIALLY STRIPPED OF PETROLEUM RESINS, AND SEPARATING FROM THE REMAINING N-BUTANOL SOLUTION OF EXTRACTED RESINS A PLURALITY OF PETROLEUM RESIN FRACTIONS BY PROGRESSIVELY DECREASING THE TEMPERATURE OF SAID N-BUTANOL SOLUTION OF PETROLEUM RESINS FROM ABOUT 240* F. TO ABOUT ROOM TEMPERATURE.
 4. PETROLEUM RESINS PREPARED ACCORDING TO THE METHOD OF CLAIM 1, RANGING BETWEEN 400 AND 1200 IN MOLECULAR WEIGHT, 60* F. AND 200* F. IN ASTM (D36-26) RING AND BALL SOFTENING POINT, 1.4900 AND 1.6200 IN REFRACTIVE INDEX ND AT 176* F., AND 0.9900 AND 1.0600 IN 